Gas-operated self-loading firearm



1946- H. L. CROCKETT GAS-OPERATED SELF-LOADING FIREARM F'il ed Feb. 1,1945 2 Sheets-Sheet l Arromvcy;

Feb. 19, 1946. H. CROCKETT GAS-OPERATED SELF-LOADING FIREARM 2Sheets-Sheet 2 Filed Feb. 1, 1945 Patented Feb. 19, 1946 GAS-OPERATEDSELF-LGADING FIREARM Harry L. Crockett, New Haven, Conn, assignor toOlin Industries, Inc., New Haven, Conn, a corporation of DelawareApplication February 1, 1945, Serial No. 575,602

9 Claims.

The present invention relates to improvements in self-doading firearmsand relates more particularly to improvements in self-loading firearmsof the type wherein gas-pressure from the bore of the barrel serves toactuate a piston which, in turn, actuates the breech-bolt and associatedfeatures of the firearm to eiiect the extraction and ejection of thejust-fired cartridge, preparatory to the automatic reloading of thefirearm with a fresh cartridge.

One of the objects of the present invention is to provide a superiorfirearm of the character referred to and in which the parts areconstructed and arranged to minimize distortion of the bolt-operatingslide under the stresses imposed thereon by the gas-operated piston.

Another object of the present invention is to provide a gas-operatedself-loading firearm with a superior construction and arrangement ofparts whereby the gas-operated piston applies its thrust upon abolt-operating slide at a point laterally intermediate the guide-meansfor the said slide and the portion of the said slide which isoperatively connected to the breech-bolt to operate the same, to therebyminimize flexing strains upon the said action-slide and to insurereliable operation of the firearm.

With the above and other objects in view, as will appear to thoseskilled in the art from the present disclosure, this invention includesall features in the said disclosure which are novel over the prior art.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1 is a broken elevational View of the central portion of agas-operated self-loading firearm embodying the present invention andlooking toward the right side thereof;

Fig. 2 is a top or plan view of the showing of Fig. 1;

Fig. 3 is a View similar to Fig. 1 but looking toward thefirearm-structure from the left side thereof;

Fig. 4 is a view of the showing of Fig. 3 mainly in underside and partlyin horizontal section on the line 4-4 of Fig. 3;

Fig. 5 is a transverse sectional view taken on the line 5-5 of Fig. 3;

Fig. 6 is a similar view taken on the line 6-6 of Fig. 3; and

Fig. 7 is a broken perspective view of the forward-portion of theaction-slide.

The particular gas-operated self-loading firearm herein chosen forpurposes of illustrating one form of the present invention, includes areceiver I (ha barrel I I, a trigger-plate unit i2, an action-slide l3,and a breech-bolt [4.

The receiver l0 above referred to includes a top-wall l5 and integralside-walls l6 and [1. The forward-portions of the top-wall l5 and theside-wall H are cut away to provide an ejectionopening I8. The saidejection-opening is closed by the breech-bolt l4 when the latter is inits forward or breech-closing position, but the said ejection-opening isopen when the said breechbolt is in its rearward position, in a mannercommon in the art.

The side-wall E6 of the receiver I0 is formed adjacent the forward endof the ejection-opening l8, with a forwardly-facing locking-abutment I9,while the opposite side-Wall I? is formed at a similar location with aforwardly-facing locking-abutment 2!). The locking-abutments l9 and 20are adapted to be engaged by the respective rear-faces or edges ofbolt-locking lugs 2| and 22. The said bolt-locking lugs 2i and 22 areformed integral with and respectively project insubstantially-diametrically-opposite directions from the forward-portionof the breech-bolt l4.

Extending radially outwardly from the outerend of the bolt-locking lug22 is an integral boltoperating lug 23 which projects into a cam-recess24 formed in the inner-face of the enlarged rearportion 25 of theaction-slide I3 before referred to.

The bolt-operating lug 23 of the breech-bolt l4 and the cam-recess 24 inthe rear-portion 25 of the action-slide i tures embodied in thewell-known Garand military rifie, and coact in such manner that when theaction-slide i3 is moved rearwardly from the position in which it isshown in the drawings, the said cam-recess will coact with theboltoperating lug 23 to first turn the breech-bolt M in a clockwisedirection (as viewed from the front) to disengage the bolt-locking lugs2| and 22 respectively from the locking-abutments l9 and 20 of thereceiver Hi. Following this unlocking movement of the breech-bolt, thecoaction of the bolt-operating lug 23 and the surfaces of the cam-recess2e will then efiect the direct rearward movement of the breech-bolt [4until the latter reaches the limit of its rearward movement. Conversely,when the action-slide is moved forwardly, following the abovedescribedrearward movement thereof, the coaction of the bolt-operating lug 23 andthe cam-recess 24 will first draw the said breech-bolt forwardly untilsuch time as the respective rear-faces of its bolt-locking lugs 2i and22 respectively register with the locking- 3, generally correspond tofea-- abutments l9 and 20 of the receiver l6, whereupon the breech-boltM will be turned transversely in a counterclockwise direction to againlock the breech-bolt in its breech-closing position.

The enlarged rear-portion 25 of the actionslide 13 is integrallyconnected by means of a.

bar-portion 26 to a crosshead 21 forming the foremost part of theaction-slide 13... The rearportion 215' and the-har-portion 2.5 of theaction;- slide l3 are mounted for reciprocation adjacent the right'sideof the barrel I l, and the crosshead 21 extends laterally from theforward-portion of" the said bar-portion 26 beneath the. saidbarrelto apoint adjacent the left side of the latter- The upper-face of thecrosshead '21: :is' for-med with a longitudinal upwardly-openingclearancegroove 28 which serves to accommodate the ad.- jacent portionof the barrel 151i andl-permit-lthe free reciprocating movement of thesaid cross:- he'ad with respect to the said barrel.

.Atia. point forwardly of. the. receiver Jill :and

also-forwardly of. the crosshead. of. the-actionslide l3, therbarnel H;:isiformed withandnteeral depending cylinder-lug .29 which .suficientbreadth to extendnla-terall-y' beyond either side of the barrel lt-propenq'as isv especially-wellslrown in Fig. 6. Thesaidcylinder-l-ug,is formedqat. :a point directly beneath; the center line of the-bar:-rel ll; :a downwardly-opening; internaliythneadedi coupling; socket-3.0; which is adapted to receive any, suitable coupling-screw(notshownr) which. may serve: to attach auitahlevstock Qalso not shown)to the barrel H.

In: its. lower right-hand portion, the cylinderl ug, 29 is formed, witha-piston-chamber which has: itsaxis extending in substantial parallelismwith the longitudinal axis. of the barrel; 1 and which opens through therear-iaceoi the cylinder-lug thesis: especially wellshownrin Fig; 4.Reciprocating in theipiston-chamber3i! :isra piston generally designatedby the reference char- :aoter. 32 and includingrelatively-largee-diametenedahead; 33;:and an integral relatiyelysma'l-l- -diametered stem 34.. 'mieheadi 33'. constitutes theforward-portion. of the piston-1.32:, "while. the: stem 34:pnoieotsrearwardly and hasits' rear -eendcnormaily' engaged; with theiorwardefane. of the crosshead 21. of" the. actionrslide. 13:.

The rear-portion of; the. pistonchamherfiil "in the cylinder-lug 2'19:is; enlarged and internally threaded :to. receive. ring-likeexternallythreaded stop-member L35. adapted. "to have: its

forward-face engaged by the reareface .of the head. of the piston 32'when the said piston. is

driven :rearvmardl-y, in a manner as. hereiniatter appean Eon-thepnrposez'ofoausing gas. .under pressure -toimpinge againsttheiorwardiendor the piston 32,. to thus drive "the said pistonrearwardlmthe cylinder-lug: 2-93 .of. the banal. ill :is formedwith an:inclined gasepassage 35. which communicates at its: lower'end with the:fonvardxendwof the pistonchamber which communicates at its upend withthe bore 37 of the barrel 41., as is indicatedin Figs. 1.14 and: 6.

In its lowerilefit-hand portion, theIfYllIIdGD-lllg 2d of the barrel idis formed with a socket '38 extending the said cylinder-lug from frontwtoxrear insubstantial parallelismwith. the hone;- 35! of thexberrel ii.Supported'iin the; socket -38: in the oylinderelng: 'fi: :is. theforward end of a'gufdesrod. zed-which hasuits rear .end' threaded andentered. internally-threaded socket All formed in the. forwardlower-portion of :the receiver .lal) adfiacentthe left side thereof, asis .head 21 of the action-slide I3, as is especially well shown in Figs.4 and 5'.

In :itslowerright-hand portion, the crosshead 21 of the action-slide I3is formed with a rearwardly-opening-socket 42 which is adapted to re-'ceivea stud lfi formed integral with and projecting' forwardly from thefront end of a breechclosing plunger- 4A. At the base of the said stud43 the breech-closing plunger 44 just referred to i's'formed with anintegral collar '45 having its vterwancl-face engaged with. therear-iaceof the crosshead 2?!- and havingits rear-face, ;in turn, engaged bytheiorward. end of ahelical breechclosing spring d6. Thesaidbreech-closingspring encircles themain-portion of the. said plunger 44and extends at its rear into a forwardly-openin fipr-ins-wpocket 4formed in the lower rig-hthand pcrtion oirthe right side-wall H ofthereceiver in, .as is especially well shown-in The rear end of thebreech-closingyplunger M is also normally entered into; theforward-portion of. the spring-pocket fil -and is adapted to slidefurther rearwardly into. the sa-id- .spring pocket when-the action-slidel3-ispmoved rearwardly.

As. thus constructed and arrangedthe' :breechclosingspring 46, actingthrough the intermediary of: the breech-closingplunger 44 and thecrosshead 2--'!-, acts to yieldingly hold the actionslide 113 initsforward position and hence, also, to. yield-ingly hold the.breech-bolt M in its breech- .closing' position.

When the -;-firearm isdischarged in any suitable ..manne1:, gas" under.pressure will pass from, the

bore 31- of the barrel. H into the forward end of the. piston-chamber3.1: in the. oylinder lug 2.9. The. saidgas will impinge against theforwardface of the head 33 of the piston .3i2 and drive the said piston.rearwardly a short distance, until: the

rear-wface-ofthe head 33iengages with theforwardface, .of .thelstopmemhe.r 35. The .desori'bedrearward: movement of the piston s2: willcause. the

rear-face of the stem 34 to drive against-the ion ward'azfiace of the'crosshead 2:1 at-a point. closely inl-i-ne. with the: breech-closingspring, 11.6 butat apoint laterally intermediate said spring and theguides-rod .39.

Thedcscribednrearwardmovement ofthepiston 332. will drive theaction-slide rearward-1y and impart thereto a :nearwardmovement far inexcess of: the relatively-short movement. of the piston 32 itself. Asthe action-slide moves rearwardly, the :crosshead. .21. will. slide onthe "guide-rod 39 .and'will also: drive the zbreecheclosing plunger Mrearwardly, to effect the compression of the breechaclosing. spring 4:6.

The rearward movement of the action-slide I 13 will unlock and retirethe breech-bolt 14.. Up

onkthecompletionof itsrearw-ard movement, the action-slide [3 will be.reversed and moved 'forwardlyby'the action of the breech-closing spring46, to thereby again restore the parts to the posiwhich they are shownin the drawings, preparatory toanother discharge" of the firearm.Bylocating'the: guid'e rod 39 piston 32 and breech-closing spring in themanner shown and'described, the said piston is caused to exert itsrelatively-violent rearward force in substantial alignment with both thebreech-closing springs stand the bar-portion 26 of the actionslide,while the opposite side of the crosshead 21 is being steadied and guidedby the guide-rod 35. In this manner, the distortion of the actionslideis so minimized as to enable the action-slide to function smoothly andwithout requiring that the said action-slide be excessively heavy inorder to withstand excessive fiexural and cramping strains.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

1. A gas-operated self-loading firearm, including in combination: areceiver; a barrel projecting forwardly from the said receiver; acylinderlug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber havingits longitudinal axis extending in substantial parallelism with thelongitudinal axis of the said barrel, the longitudinal axis of the saidpistonchamber being located in a plane to one side of the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guiderod having its longitudinal axis extending in substantialparallelism with the longitudinal axis of the said barrel and located onthe opposite side of the vertical longitudinal plane extending throughthe longitudinal axis of the said barrel, the said guide-rod having itsforward-end engaged with the said cylinder-lug and having its rear-endengaged with the forward-portion of the said re ceiver; a breech-boltmovable longitudinally in the said receiver; an action-slide mounted forlongitudinal reciprocation along one side of the said receiver andhaving a bearing-portion slidably engaging with the said guide-rod, thesaid action slide being operatively connected to the said breech-boltfor moving the same; a piston movable in the piston-chamber of the saidcylinderlug and normally engaged with a forward-portion of the saidaction-slide to drive the latter rearwardly; and gas-conducting meansextending between the bore of the said barrel and the forward-portion ofthe piston-chamber in the said barrel-lug.

2. A gas-operated self-loading firearm, including in combination: areceiver; a barrel projecting forwardly from the said receiver; acylinder-lug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber havingits longitudinal axis extending in substantial parallelism with thelongitudinal axis of the said barrel, the longitudinal axis of the saidpistonchamber being located in a plane to one side of the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guiderod haw'ng its longitudinal axis extending insubstantial. parallelism with the longitudinal axis of the said barreland located on the opposite side of the vertical longitudinal planeextending through the longitudinal axis of the said barrel, the saidguide-rod having its forward-end engaged with the said cylinder-lug andhaving its rear-end engaged with the forward-portion of the saidreceiver; a breech-bolt movable longitudinally in the said receiver; anaction-slide mounted for longitudinal reciprocation along the side ofthe firearm-structure on which the said piston-chamber is located, thesaid action-slide being operatively connected at its rear with the saidbreechbolt and having adjacent its forward-end a bearing-portionslidably engaging with the said guiderod; a piston movable in thepiston-chamber of the said cylinder-lug and normally engaged with aforward-portion of the said action-slide to drive the latter rearwardly;and gas-conducting means extending between the bore of the said barreland the forward-portion of the piston-chamber in the said barrel-lug.

3. A gas-operated self-loading firearm, including in combination: areceiver; a barrel projecting forwardly from the said receiver; acylinderlug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber havingits longitudinal axis extending in substantial parallelism with thelongitudinal axis of the said barrel, the longitudinal axis of the saidpistonchamber being located in a plane to one side of the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guiderod having its longitudinal axis extending in substantialparallelism with the longitudinal axis of the said barrel and located onthe opposite side of the vertical longitudinal plane extending throughthe longitudinal axis of the said barrel, the said guide-rod having itsforward-end engaged with the said cylinder-lug and having its rear-endengaged with the forward-portion oi the said receiver; a breech-boltmovable longitudinally in the said receiver; an action-slide mounted forlongitudinal reciprocation along One side of the said receiver andhaving a head-portion adjacent its forward-end which head-portion isprovided with a bearing-portion slidably engaging with the saidguide-rod, the said action-slide being operatively connected adjacentits rearend to the said breech-bolt for moving the same; a pistonmovable in the piston-chamber of the said cylinder-lug and normallyengaged with the head-portion of the said action-slide to drive theaction-slide rearwardly; and gas-conducting means extending between thebore of the said barrel and the forward-portion of the piston chamber inthe said barrel-lug,

4. A gas-operated self-loading firearm, including in combination: areceiver; a barrel projecting forwardly from the said receiver; acylinder-lug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber havingits longitudinal axis extending in substantial parallelism with thelongitudinal axis of the said barrel, the longitudinal axis of the saidpistonchamber being located in a plane to one side of the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guiderod having its longitudinal axis extending in substantial parallelism with the longitudinal axis of thesaid barrel andlocated on the opposite side of the vertical longitudinal planeextending through the longitudinal axis of the said barrel, the saidguide-rod having its forward-end engaged with the said cylinder-lug andhaving its rear-end engaged with the forward-portion of the saidreceiver; a. breech-bolt movable longioneness side ofthefirearm-structure on which thezsaid piston-chamberis located: andhaving aheadportion adjacent; its fnrwardeend which. head;- porin'onextends transversely beneath the barrel into bearing engagement with thesaid guide-rod, said action-slide being operatively connected adjacentits rear-end to. the said; breech-boltfor moving th same; apistonqmovable in the/pistonchamher or the saidT-cylinder-lug andnormally engaged with the head-portion of the said-actionslide to drive:the; action-slide rear-wardly; and gas conducting means extendingbetween. the of the said barrel and the; forward-portion of the.pistonech-amber in the said barrel-lug.

5. A gas-operated self-loadingfirearm-,pinGludincomhinationz; areceiver; a barrelprojecting forwardly from thesaid receiver; acylinderlug depending from the said barrel at a. point forwardly of thesaid receiver; and formed with a rearward-wh tening, piston echamberhaving its longitudinal, axisex-tending in substantial parallelism withthe longitudinal axis of the said barrel, the longitudinal axis of the.said pistonchamber being located in apl'aneto one side or the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guiderod having its longitudinal, axisextendingin substantialparallelism with the, longitudinal axis of the said barrel and locatedon the, opposite side of the vertical longitudinal plane, extendingthrough the longitudinal axis of the said barrel, the said guide-rodhaving its forward-end envgaged with the said cyl-in-derelug. and.having its rear-end engaged with the forward-portion of the saidreceiver; abreech-bolt movable longitudinally in the said receiver; anaction-slide mounted for longitudinal reciprocation along one side of'the said receiver and having a bearingportion slidably engaging with thesaid guiderod, the said action-slide being operatively connected to thesaid breech-bolt for moving the same; a helical breech-closing spring.thrusting forwardly upon the said action-slide and extend ing insubstantial parallelism with the saidguiderod but located on theopposite side of the firearm-structure therefrom; a piston movable inthe piston-chamber of the said cylinder lug vand normally engaged with-aforward-portion of the said action-slide to drive. the latterrearwardly; and gas-conductingimeans extending between the bore of thesaid barrel and the forward-portion of the piston-chamber-in the saidbarrel-lug.

'6. Al gas-operated self-loading firearm, including in combination:a'receiver; a barrel projecting forwardly from the said receiver; acylinder-lug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber havingits longitudinal axis extending in substantial parallelism with thelongitudinal axis of' the said barrel, the longitudinal axis of the saidpiston-chamber being located in a plane to one 'sideof the verticallongitudinal plane extending through the longitudinal axis of the saidbarrel; a guide-rod havingits longitudinal axis extending in substantialparallelismwiththe longitudinal axis of the said barrel and located onthe opposite side of the vertical longitudinal plane extending throughthe longitudinal" axis of the said barrel, the said guide-rod having itsforward-end engaged with the cylinder-lug andhaving its rear-end engagedthe forward-portion of the said receiveni a breecmbolt; movablelongitudinally in the; said receiver; an. action-slidemounted forlongitudinal, reciprocation along the side of the firearmestructure onwhich-the said piston-chain.- ber is located, the; saidaetion-slide;being operatively-connected attits'. rear with the said breech- .boltand having adjacent its forward-end a bearing-portion slidably' engagingwith the said guide,- rod; a. helical breech-closing spring, thrustingforwardly upon; thevsaid action-slide and extending 'in substantialparallelism with the said guiderod but located on the opposite side oftheme? arm-structure. therefrom; a piston movable in the'piston-chamberof the-said cylinder-lug; and normally engaged: with a:forward-portioniof the said. action-slide to drive the latterrearwardly;

and gas-conducting means. extending between the bore: of thesaid barreland thevforward-pertion of the. piston-chamber in the: said barrel- 7. Agas-operatedself-loading firearm; include ing in combination; areceiver; a barrel projecting- Iorwardly from the, said receiver; acylinderlug depending fromthe said barrel at a point forwardly ofthe-said receiver and formed with a rearwardly-openi-ng piston-chamberhaving its longitudinal axis extending: in substantial, parallelism withthe longitudinal axi of the-said bar-- rel, thelongitudinal axis of thesaid piston-chain her being located in a, plane to one side of thevertical longitudinal plane extending through-the longitudinal axis ofthe said barrel; a guide-rod havingitslongitudinal axis extending insubstantial parallelism with the longitudinal axis of the said barreland located on the opposite side of the, vertical longitudinal. planeextending through the longitudinal axis of the said. barrel, the, said 7guide-rod havingi'ts forward-end engaged with the said cylinder-lug andhaving its rear-endangaged with the forward-portion of. the saidreceiver; a, breech-bolt movable longitudinally in the said receiver;van action-slide mounted for longitudinal reciprocation along one side.of the said receiver and having .a head-pontionadjacent .its forward-endwhich'head-port'ion is provided witha bearing-portion slidably engagingwith the said guide-rod, the said .actionrslide being operativelyconnected adj acentits rear-end to the said. breech-bolt for moving thesame; a helical breechrclos'ing, spring thrusting. forwardlyupon thehead-portion oi thev said action-slide andextending, in substantialparallelism with. the-- said guiderrod but located on. the oppositesidesof the firearm-structure therefrom; a, piston movable in thepiston-chamber of the said cylinder-lug and normally engaged with thehead-portion of the said action-slide to drive the, action-slide.rearwardly; and gas-conducting meanslextend'ing be. tween the bore ofthe said barrel. and the forward-portion of the piston-chamber in thesaid barrel-lug.v

'8. A gas-operated self-loading firearm, includ- 1 ing in combination;receiver; a barrel projecting forwardly from the said receiver; a.cylinderlug depending from the said-barrel. at a point forwardly of thesaid receiver and formed with a rearwardht-opening piston-chamberhaving. its longitudinal axis extendingin substantial. parallelism withthe longitudinal axis. of. the said barreLtheJongitudinaI axis. of thesaid piston-chamber being located in a plane to one side-of the 7vertical longitudinal plane extending throughthe longitudinal axisof thesa'idbarrel; aguide-rod having-its longitudinal axis extending insubstantialparallelism with the longitudinal axis of the said barrel andlocated on the opposite side of the vertical longitudinal planeextending through the longitudinal axis of the said barrel, the saidguide-rod having its forward-end engaged with the said cylinder-lug andhaving its rear-end engaged with the forward-portion of the saidreceiver; a breech-bolt movable longitudinally in the said receiver; anaction-slide mounted for longitudinal reciprocation along the side ofthe firearm-structure on which the said piston-chamber is located andhaving a head-portion adjacent its forward-end which head-portionextends transversely beneath the barrel into bearing engagement with thesaid guide-rod, the said action-slide being operatively connectedadjacent its rear-end to the said breech-bolt for moving the same; ahelical breech-closing spring thrusting forwardly upon the head-portionof the said action-slide and extending in substantial parallelism withthe said guide-rod but located on the opposite side of thefirearm-structure therefrom; a piston movable in the piston-chamber ofthe said cylinder-lug and normally engaged with the head-portion of thesaid action-slide to drive the action-slide rearwardly; andgas-conducting means extending between the bore of the said barrel andthe forward-portion of the pistonehamber in the said barrel-lug.

9. A gas-operated self-loading firearm, including in combination: areceiver; a barrel projecting forwardly from the said receiver; acylinder lug depending from the said barrel at a point forwardly of thesaid receiver and formed with a rearwardly-opening piston-chamber andwith a rod-receiving passage, both the said pistonchamber and therod-receiving passage extending in substantial parallelism with thelongitudinal axis of the said barrel and respectively located onopposite sides of the vertical longitudinal plane extending through thelongitudinal axis of the said barrel; a guide-rod having itslongitudinal axis extending in substantial parallelism with thelongitudinal axis of the said barrel and having its rear-end threadedlyengaged with the forward-portion of the said receiver'and having itsforward-end located in the rod-receiving passage of the saidcylinder-lug; an action-slide mounted for longitudinal reciprocationalong one side of the said receiver and having a head-portion adjacentits forward-end which head-portion is provided with a. bearing-portionslidably engaging with the said guide-rod, the said action-slide beingoperatively connected adjacent its rear-end to the said breech-bolt formoving the same; a piston movable in the piston-chamber of the saidcylinder-lug and normally engaged with the headportion of the saidaction-slide to drive the action-slide rearwardly; and gas-conductingmeans extending between the bore of the said barrel and theforward-portion of the piston-chamber in the said barrel-lug.

' HARRY L. CROCmTT.

